1. Field of the Invention
The present invention is related to a vehicle navigation system, in particular, to a technique for upgrading a vehicle navigation system.
2. Description of the Related Art
Vehicle navigation systems are provided with storage devices containing navigation software programs and map data.
A hard disk drive is a typical storage device used in a vehicle navigation system. A navigation system with a built-in hard disk drive uses a navigation program and map data stored in the hard disk drive to navigate a vehicle to a destination.
One of drawbacks of a navigation system with a built-in hard disk drive is that the navigation system can not work during upgrade. Upgrading a navigation system with a built-in hard disk drive involves detaching the hard disk drive from the system, updating a navigation program and map data in the hard disk drive, and restoring the hard disk drive to the system. Detaching the hard disk drive prohibits the navigation system from operating during the upgrade. This implies that the navigation system is forced to quit navigating a vehicle during the upgrade of the system. Furthermore, this upgrade procedure undesirably requires a user to hand over the vehicle to a dealer to have the hard disk drive updated.
Therefore, a need exists to provide a technique for effectively reducing the time during which a navigation system is forced to quit operating in order to upgrade the system.
An optical disk drive, such as a DVD-ROM drive, is another typical storage device used in a vehicle navigation system. A navigation system with a built-in DVD-ROM drive uses a navigation program and map data stored in a DVD-ROM to navigate a vehicle to a destination. Upgrading the navigation system with the built-in DVD-ROM drive can be achieved by replacing the DVD-ROM with a new DVD-ROM containing a new navigation program and new map data. Therefore, a navigation system with a built-in DVD-ROM drive is superior to that with a built-in hard disk drive in terms of necessary time for upgrading the system. Nevertheless, DVD-ROM drives are inferior to hard disk drives in terms of access time, and this undesirably leads to a slow operation speed of the system. Therefore, a navigation system desirably operates using a hard disk drive to improve operation speed.
Navigation systems provided with both a hard disk drive and a DVD-ROM drive are disclosed in Japanese Unexamined Patent Applications No. 2001-133273 and 2001-165671. The disclosed navigation systems transfer map data stored in a DVD-ROM to a hard disk drive, and executes vehicle navigation using transferred map data in the hard disk drive. These navigation systems allows users to play another DVD-ROM during vehicle navigation.
Japanese Unexamined Patent Application No. 2000-251396 discloses an in-vehicle information processing unit for achieving reliable data write into a hard disk drive.